Effects of variation in particle size on biaxial flexural strength of two conventional glass-ionomer cements.

Conventional glass-ionomer cements (GICs) have a slow maturation time. Reduction in time of maturation may be achieved by acceleration of the setting reaction. One factor that assists this is the reduction in glass particle size producing a larger surface area for reaction. The resulting rapid set and more rapid maturation should potentially lead to less long-term degradation. Biaxial strength measurements were made with respect to time for two GICs of similar compositions but with differing particle size distributions at different time intervals after immersion in both water and artificial saliva. There was little difference between the strength of the two materials over periods up to 12 weeks. A theoretical estimation of the relative surface areas of glasses showed that, despite there being twice the surface area available for reaction for one glass, there was little difference in strengths values between the two materials at any of the times tested here. The similarity in strength values despite this substantial difference suggests that the larger particles may have a greater influence in the cement forming process.